Many theories have been formulated to explain the role of grazers such as zooplankton in controlling the amount of planktonic algae (phytoplankton) in lakes. The first theories of such grazer control were merely based on observations of negative correlations between algal and zooplankton numbers. A low number of algal cells in the presence of a high number of grazers suggested, but did not prove, that the grazers had removed most of the algae. The converse observation, of the absence of grazers in areas of high phytoplankton concentration, led Hardy to propose his principle of animal exclusion, which hypothesized that phytoplankton produced a repellent that excluded grazers from regions of high phytoplankton concentration. This was the first suggestion of algal defenses against grazing.
Perhaps the fact that many of these first studies considered only algae of a size that could be collected in a net (net phytoplankton), a practice that overlooked the smaller phytoplankton (nannoplankton) that we now know grazers are most likely to feed on, led to a de-emphasis of the role of grazers in subsequent research. Increasingly, as in the individual studies of Lund, Round, and Reynolds, researchers began to stress the importance of environmental factors such as temperature, light, and water movement in controlling algal numbers. These environmental factors were amenable to field monitoring and to simulation in the laboratory. Grazing was believed to have some effect on algal numbers, especially after phytoplankton growth rates declined at the end of bloom periods, but grazing was considered a minor component of models that predicted algal population dynamics.
The potential magnitude of grazing pressure on freshwater phytoplankton has only recently been determined empirically. Studies by Hargrave and Geen estimated natural community grazing rates by measuring feeding rates of individual zooplankton species in the laboratory and then computing community grazing rates for field conditions using the known population density of grazers. The high estimates of grazing pressure postulated by these researchers were not fully accepted, however, until the grazing rates of zooplankton were determined directly in the field, by means of new experimental techniques.Using a specially prepared feeding chamber, Haney was able to record zooplankton grazing rates in natural field conditions. In the periods of peak zooplankton abundance, that is, in the late spring and in the summer, Haney recorded maximum daily community grazing rates, for nutrient-poor lakes and bog lakes, respectively, of 6.6 percent and 114 percent of daily phytoplankton production. Cladocerans had higher grazing rates than copepods, usually accounting for 80 percent of the community grazing rate. These rates varied seasonally, reaching the lowest point in the winter and early spring. Haney‘s thorough research provides convincing field evidence that grazers can exert significant pressure on phytoplankton population. (461 words)
1. It can be inferred from the passage that the ―first theories‖ of grazer control mentioned in the first paragraph would have been more convincing if researchers had been able to
(A) observe high phytoplankton numbers under natural lake conditions
(B) discover negative correlations between algae and zooplankton numbers from their field research
(C) understand the central importance of environmental factors in controlling the growth rates of phytoplankton
(D) make verifiable correlations of cause and effect between zooplankton and phytoplankton numbers
(E) invent laboratory techniques that would have allowed them to bypass their field research concerning grazer control
For the following question, consider each of the choices separately and select all that apply
2. The author would be likely to agree with which of the following statements regarding the pressure of grazers on phytoplankton numbers?
□A Grazing pressure can vary according to the individual type of zooplankton.
□B Grazing pressure can be lower in nutrient-poor lakes than in bog lakes.
□C Grazing tends to exert about the same pressure as does temperature.
答案解析：通过人名直接定位，L11 的人名，往上L9 开始这一句话，converse 告诉我们这里H 是想证明另外一种数量上(浮游植物多，就会造成浮游动物的减少)的负相关，也就是浮游植物会干掉浮游动物。选项B 道出了，浮游动物的减少与浮游植物无关，直接质疑了H 的这个观点。
3. It can be inferred from the passage that one way in which many of the early researchers on grazer control could have improved their data would have been to
(A) emphasize the effects of temperature, rather than of light, on phytoplankton
(B) disregard nannoplankton in their analysis of phytoplankton numbers
(C) collect phytoplankton of all sizes before analyzing the extent of phytoplankton concentration
(D) recognize that phytoplankton other than net phytoplankton could be collected in a net
(E) understand the crucial significance of net phytoplankton in the diet of zooplankton
答案解析：A. 定位在L50-L55，体现不同生活环境不同种类的浮游植物都是不同的。B. 定位同上，很简单的比较。C. 文章没有提到same 的感觉。
4. According to the passage, Hargrave and Geen did which of the following in their experiments?
(A) They compared the grazing rates of individual zooplankton species in the laboratory with the natural grazing rates of these species.
(B) They hypothesized about the population density of grazers in natural habitats by using data concerning the population density of grazers in the laboratory.
(C) They estimated the community grazing rates of zooplankton in the laboratory by using data concerning the natural community grazing rates of zooplankton.
(D) They estimated the natural community grazing rates of zooplankton by using data concerning the known population density of phytoplankton.
(E) They estimated the natural community grazing rates of zooplankton by using laboratory data concerning the grazing rates of individual zooplankton species.
答案解析： 定位在第二段首，说忽略了small 浮游植物。改善题直接取非。选C。
Spiders of many species change color to match the pigmentation of the flowers they sit on. The insects preyed on by those spiders, unlike human beings, possess color discrimination so acute that they can readily see the spiders despite the seeming camouflage. Clearly, then, it must be in evading their own predators that the spiders‘color changes are useful to them.
5. Which of the following, if true, most strengthens the argument?
(A) Among the animals that feed on color-changing spiders are a few species of bat,which find their prey through sound echoes.
(B) Certain animals that feed on color-changing spiders do so only sparingly in order to keep from ingesting harmful amounts of spider venom.
(C) Color-changing spiders possess color discrimination that is more acute than that of spiders that lack the ability to change color.
(D) Color-changing spiders spin webs that are readily seen by the predators of those spiders.
(E) The color discrimination of certain birds that feed on color-changing spiders is no more acute than that of human beings.
答案解析：通过人名定位L37，一个长难度(杨鹏GRE、GMAT长难句序言的例句)，“Studies by Hargrave and Geen estimated natural community grazing rates(目的) by(方法) measuring feeding rates of individual zooplankton species in the laboratory and then(两个步骤) computing community grazing rates for field conditions using the known population density of grazers(两个黄色部分重复).”
The belief that art originates in intuitive rather than rational faculties was worked out historically and philosophically in the somewhat wearisome volumes of Benedetto Croce, who is usually considered the originator of a new aesthetic. Croce was, in fact, expressing a very old idea. Long before the Romantics stressed intuition and self-expression, the frenzy of inspiration was regarded as fundamental to art, but philosophers had always assumed it must be controlled by law and by the intellectual power of putting things into harmonious order. This general philosophic concept of art was supported by technical necessities. It was necessary to master certain laws and to use intellect in order to build Gothic cathedrals, or set up the stained glass windows of Chartres. When this bracing element of craftsmanship ceased to dominate artists‘ outlook, new technical elements had to be adopted to maintain the intellectual element in art. Such were linear perspective and anatomy.(156 words)
6. The passage suggests that which of the following would most likely have occurred if linear perspective and anatomy had not come to influence artistic endeavor?
(A) The craftsmanship that shaped Gothic architecture would have continued to dominate artists‘ outlooks.
(B) Some other technical elements would have been adopted to discipline artistic inspiration.
(C) Intellectual control over artistic inspiration would not have influenced painting as it did architecture.
(D) The role of intuitive inspiration would not have remained fundamental to theories of artistic creation.
(E) The assumptions of aesthetic philosophers before Croce would have been invalidated.
7. Select the sentence in the passage that indicates a traditional assumption of aesthetic philosophers.
正确答案：Long before the Romantics
答案解析：通过“traditional assumption of aesthetic philosophers”定位L6
8. The author mentions ―linear perspective and anatomy‖ in the last sentence in order to do which of the following ?
(A) Expand his argument to include painting as well as architecture
(B) Indicate his disagreement with Croce‘s theory of the origins of art
(C) Support his point that rational order of some kind has often seemed to discipline artistic inspiration
(D) Explain the rational elements in Gothic painting that corresponded to craftsmanship in Gothic architecture
(E) Show the increasing sophistication of artists after the Gothic period
答案解析：定位倒数第二句话：A. 没有painting;B. 距离Croce 比较远，并且该句话没有讨论起源;C. 答案;对应着文章的主旨：rational order 对inspiration 的discipline 的关系;D. 没有题painting，不知道那个stained glass 算不算painting，并且craftsmanship已经cease 了，这里不是指它。E. 没有明显after G period 的感觉。
Nahuatl, like Greek and German, is a language that allows the formation of extensive compounds. By the combination of radicals or semantic elements, single compound words can express complex conceptual relations, often of an abstract universal character.
The tlamatinime (―those who know‖) were able to use this rich stock of abstract terms to express the nuances of their thought. They also availed themselves of other forms of expression with metaphorical meaning,some probably original, some derived from Toltec coinages. Of these forms the most characteristic in Nahuatl is the juxtaposition of two words that, because they are synonyms, associated terms, or even contraries, complement each other to evoke one single idea. Used as metaphor, the juxtaposed terms connote specific or essential traits of the being they refer to, introducing a mode of poetry as an almost habitual form of expression.(140 words)
9. According to the passage, some abstract universal ideas can be expressed in Nahuatl by
(A) taking away from a word any reference to particular instances
(B) removing a word from its associations with other words
(C) giving a word a new and opposite meaning
(D) putting various meaningful elements together in one word
(E) turning each word of a phrase into a poetic metaphor
For the following question, consider each of the choices separately and select all that apply
10. It can be inferred solely from the information in the passage EXCEPT that
□A all abstract universal ideas are ideas of complex relations
□B some record or evidence of the thought of the tlamatinime exists
□C metaphors are always used in Nahuatl to express abstract conceptual relationships
答案解析： Except 题：A. All 太绝对;B. L7;C. 还是上述定位，文章说“They also availed themselves of other forms of expression with metaphorical meaning”
Since science tries to deal with reality, even the most precise sciences normally work with more or less imperfectly understood approximations toward which scientists must maintain an appropriate skepticism. Thus,for instance, it may come as a shock to mathematicians to learn that the Schrodinger equation for the hydrogen atom is not a literally correct description of this atom, but only an approximation to a somewhat more correct equation taking account of spin, magnetic dipole, and relativistic effects; and that this corrected equation is itself only an imperfect approximation to an infinite set of quantum field-theoretical equations. Physicists, looking at the original Schrodinger equation, learn to sense in it the presence of many invisible terms in addition to the differential terms visible, and this sense inspires an entirely appropriate disregard for the purely technical features of the equation. This very healthy skepticism is foreign to the mathematical approach. Mathematics must deal with well-defined situations. Thus, mathematicians depend on an intellectual effort outside of mathematics for the crucial specification of the approximation that mathematics is to take literally. (177 words)
11. According to the passage, scientists are skeptical toward their equations because scientists
(A) work to explain real, rather than theoretical or simplified, situations
(B) know that well-defined problems are often the most difficult to solve
(C) are unable to express their data in terms of multiple variables
(D) are unwilling to relax the axioms they have developed
(E) are unable to accept mathematical explanations of natural phenomena
答案解析：定位第一句话，因为真实所以应该保持适当的怀疑。(文章后面的其实就是在讲“theoretical or simplified, situations”，一些纯理论或者忽视一些未知条件的简单状况)
12. The author implies that scientists develop a healthy skepticism because they are aware that
(A) mathematicians are better able to solve problems than are scientists
(B) changes in axiomatic propositions will inevitably undermine scientific arguments
(C) well-defined situations are necessary for the design of reliable experiments
(D) mathematical solutions can rarely be applied to real problems
(E) some factors in most situations must remain unknown
答案解析：定位在L18，看见“This”证明之前有所交代，往前看，我们知道是invisible term导致“inspires an entirely appropriate disregard for purely technical features ”，从而导致situation 不能很好的well-defined。所以答案E.